Mechanical devices are often used in physical therapy applications to assist medically or physically handicapped persons in the performance of certain activities which they would otherwise be unable to perform. In some instances, mechanical devices are used to overcome developmental shortcomings. For example, it is understood that the nervous system of each human being must go through a definite series of developmental stages before a brain can operate at its full potential. Substantial negative consequences may result from a child skipping a phase in this developmental sequence because of brain injury or lack of opportunity. For example, many of the "slow" children never had an opportunity to learn to crawl or creep well.
The treatment for such disability includes a pattern of exercises consisting of creeping and crawling and which is designed to stimulate and build up a child's neurological organization. Such treatment involves the step by step development of the central nervous system. The distinction between crawling and creeping for purposes of treatment is that in crawling, the child moves forward by pulling with the arms and pushing with the legs, both at the same time with a stomach on the floor, whereas in creeping the stomach is off the floor and the child advances by reaching with one arm and pushing with the opposite leg, and then repeating this pattern with the other arm and leg. Although important, it is often difficult to motivate the child to advance from a crawling phase to the creeping phase, that is to lift the stomach off the ground, so that it is supported by his arms and legs. Therefore, prior art devices have been used to assist children in performing creeping action by supporting a body in a creeping position.
Other studies have been conducted to determine why independent walking is delayed for blind babies. These studies have indicated that in the natural stages of development, creeping must precede walking and that blind children exhibit a marked lag in the achievement of creeping. It was found that in sighted children, the early creeping pattern results from attempts by the child to reach for out-of-range objects. Thus, early creeping is a reach and a collapse sequence which gradually smoothes out and becomes a motor pattern of creeping. However, for the blind baby, there is no stimulus for reaching so he does not have a motivation for propelling himself forward. Thus, prior art devices have been used to assist blind children in their motor development and to provide a substitute for the visual stimulus of reaching.
Devices for assisting mentally or physically handicapped children in performing creeping exercises have been disclosed, for example, in U.S. Pat. Nos. 2,843,391, 3,532,356, and 3,992,023. These devices generally include a wheeled frame from which a body support is suspended. The child is placed on the suspended body support arranged so that his hands and feet may contact the ground in order to enable him to propel the wheeled frame by movement of his arms and legs. These devices suffer from several drawbacks which include restriction of the child's head or limbs, restriction on the degree of freedom of movement, and instability. These drawbacks make these prior art devices needlessly unsafe.
Another device has been proposed for overcoming the shortcomings of the aforementioned devices, and is described, for example, in U.S. Pat. No. 4,796,903. This device is similar to the aforementioned devices in that it includes a wheeled frame from which a body support is suspended, and is used by a child in the same manner as described above. The device proved to be more comfortable, safer, and less restrictive than the aforementioned devices, and is readily adjustable and capable of being disassembled for replacement and/or cleaning of parts. Unfortunately, it also suffers from several drawbacks. First, the wheeled frame itself is prone to collapse. The wheeled frame is constructed from many parts which are bolted together. The bolts can easily come loose as the device is used. This places the child at risk, in an environment and in an application which should be as risk-free as possible. Second, the structure of the wheeled frame is such that the parts can easily be bent, which decreases its usefulness and makes it unsafe. Third, the wheeled frame must be assembled from multiple parts, which requires excessive manufacturing time and makes it difficult to clean. Finally, the straps which tailor the device to children of different sizes are cumbersome to use and can only be adjusted in predetermined increments, rather than providing for true adjustability.